Using 'Async Tasks' on Android to generate random number and output

I am writing an random number generator program to show the output every sec.

The overview is that every second when the random number change I would want to random number to be output to the 'EditText' box. Is it possible?

I have research on it but result in unsuccessfully (mainly because of how the async works).

This is the code that I have written:

package com.example;

import java.util.Random;

import android.app.Activity;
import android.os.AsyncTask;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;

public class AsyncTasksActivity extends Activity {

EditText txtMessage;

/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);         

    String ranString = "";

    try{
        ranString = "";
        for(int a = 0; a < 33; a++)
        {
        Random rn = new Random();
        int i = rn.nextInt(256);

        ranString = ranString + i + " ";

        }
    } catch (Exception e) {
        System.err.println("Error: " + e.getMessage());
    }
    txtMessage = (EditText) findViewById(R.id.txtMessage);
    txtMessage.setText(ranString);
}

public class runRandomly extends AsyncTask<String, String, String> {

    @Override
    protected String doInBackground(String... params) {
        // TODO Auto-generated method stub
        return null;
    }

    @Override
    protected void onPostExecute(String result) {
        // TODO Auto-generated method stub
        super.onPostExecute(result);
    }

    @Override
    protected void onProgressUpdate(String... values) {
        // TODO Auto-generated method stub
        super.onProgressUpdate(values);
    }

    }


}

In case you need to run the code to ensure it works, I have place the xml code here:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:weightSum="1">

<TextView开发者_运维技巧  
android:layout_width="fill_parent" 
android:layout_height="wrap_content" 
android:text="Null"
/>
<EditText 
android:id="@+id/Null"  
android:layout_width="fill_parent" 
android:layout_height="wrap_content"
android:singleLine="true"
android:inputType="numberDecimal"/>

<TextView  
android:layout_width="fill_parent" 
android:layout_height="wrap_content"         
android:text="Random Key"/>
<EditText 
android:id="@+id/txtMessage"  
android:layout_width="fill_parent" 
android:gravity="center"
android:editable="false" android:layout_height="61dp" android:layout_weight="0.14"/>

<LinearLayout  xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="horizontal"
android:layout_width="fill_parent"
android:layout_height="wrap_content">
</LinearLayout>

<LinearLayout  xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="horizontal"
android:layout_width="fill_parent"
android:layout_height="wrap_content"/>   

</LinearLayout>

Much Thanks!

From my point of view,

1. Make a constructor of your AsyncTask class passing activity signature, like,

   public runRandomly(Activity activity) {
   this.activity = activity;
   context = activity;
   }
   

2. also override this method

   @Override
   protected void onProgressUpdate(Integer... values)
   {
   
   super.onProgressUpdate(values);
   if (values[0] == 0) {
   mDialog.setTitle("Processing...");
   }
   
   mDialog.setProgress(values[0]);
   
   } 
   

3. update the onProgressUpdate(call it) from your doInBackground(String... params) method

EDIT: you can also give a reference of your EditText view in AsyncTask constructor and do update in onProgressUpdate method.

EDIT: use this code..

public class NewClass extends Activity {
/** Called when the activity is first created. */
EditText edt;
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    setContentView(R.layout.newclass);
    edt=(EditText)findViewById(R.id.ed);

    new runRandomly(this,edt).execute();
}


public class runRandomly extends AsyncTask<String, String, String> {

String ranString="";
Activity activity;
EditText edtt;

public runRandomly(Activity activity,EditText edit) {
    this.activity = activity;
    edtt=edit;
    }

@Override
protected String doInBackground(String... params) {
    // TODO Auto-generated method stub

    try{

        for(int a = 0; a < 33; a++)
        {
        Random rn = new Random();
        int i = rn.nextInt(256);

        ranString = ranString + i + " ";

        }
        onProgressUpdate();
    } catch (Exception e) {
        System.err.println("Error: " + e.getMessage());
    }

    return null;
}

@Override
protected void onPostExecute(String result) {
    // TODO Auto-generated method stub
    super.onPostExecute(result);
}

@Override
protected void onProgressUpdate(String... values) {
    // TODO Auto-generated method stub

    edtt.setText(""+ranString);
    super.onProgressUpdate(values);
}

}


}

Simple, Thanx.

put this line outside of the for loop it will re-generate new object so no need it in loop

Random rn = new Random();

for(int a = 0; a < 33; a++)
{
    int i = rn.nextInt(256);

    ranString = ranString + i + " ";
}

you need to Handler and Runnable object which call the AsynTask execute method using runRandomly object

like create this object

Handler handler = new Handler();
runRandomly randomly = new runRandomly();


Runnable callRandom = new Runnable(){
   public void run(){
        //// call the execute method 
        randomly.execute();
        ///// here handler call this runnable every 1 sec i.e 1000 delay time
        handler.postDelay(callRandom,1000);
   }
}

in onBackground generate the number @Override protected String doInBackground(String... params) { String ranString = "";

    Random rn = new Random();

    for(int a = 0; a < 33; a++)
    {
        int i = rn.nextInt(256);

        ranString = ranString + i + " ";
    }
    return ranString;
}

this above method will generate the random number string and when it finish this will return that string to the postExecute();

@Override
protected void onProgressUpdate(String values) {
    super.onProgressUpdate(values);
    if(values!=null & !values.equals(""))
       txtMessage.setText(ranString);

}